The present invention relates to an apparatus for measuring a mass flow, in particular bulk material or a fluid, and the invention especially relates to a zero setting arrangement used in a measuring device in which the mass flow rate is measured by using the Coriolis measuring principle. The arrangement according to the invention concerns both a method for zero setting and a device for implementing the method.
Such a prior measuring device is known from our copending European patent application No. 96850202.1, filed on Nov. 29, 1996, describing the main principles for such a mass flow meter, and to which application the interested reader is referred.
In such a measuring device, the particles to be measured are subjected to tangential acceleration in a whirling impeller, and the torque exerted on the vanes of the impeller in reaction to the Coriolis force of accelerated particles is measured as an indication of the mass flow rate. The object of our above European patent application was to avoid measurement errors, due to uneven distribution of the material to be measured.
Even though the accuracy in the measurements has been greatly improved by our previous device, it is still necessary to adjust the device for eliminating or reducing measurement errors due to variations in bearing friction in the bearings supporting the impeller shaft.